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Y3 Parasitology S2 > Cyathostomins > Flashcards

Cyathostomins Flashcards

1
Q

Which parasite is the horse equivalent of Teladorsagia in sheep and Ostertagia in cattle?

A

Cyathostomin spp

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2
Q

Where do the parasitic stages of Cyathostomins live in the horse?

A

Large intestine

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3
Q

Cyathostomins are a common parasite of horses of which age?

A

More than one year old

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4
Q

The eggs of Cyathostomin spp are what size?

A

80-100um

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5
Q

What are some features of the Cyathostomin spp life cycle?

A
  • Direct
  • Non-migratory – parasite stays within the GI tract
  • Infective stage is L3
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6
Q

What are the 3 further defined stages of the Cyathostomin spp lifecycle within the host?

A

Within the large intestinal mucosa the parasites stages have been further defined

  • EL3 = Early L3
  • LL3 = Late L3
  • DL4 = Developing L4
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7
Q

How are the stages of Cyathostomin visualised under magnification?

A
  • Early third stage in the mucosa (EL3) have to be digested out of the mucosa to be visible under x40 magnification
  • Developing fourth stage in the mucosa (DL4) are visible by transillumination of mucosa at x40 magnification
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8
Q

How long is the ppp of Cyathostomin spp?

A

6-8 weeks

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9
Q

Total length of Cyathostomin worms ranges from ?

A

0.5-1cm

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10
Q

Describe hypobiosis of Cyathostomin spp

A
  • Inhibited larvae may constitute >70% of total worm burden in autumn/winter in UK
  • Complex process of arrested development and reactivation not well understood
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11
Q

Which factors may contribute to the occurrence of hypobiosis?

A
  • Cold conditioning
  • Heavy parasite burden
  • Age - young horses have higher mucosal burden
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12
Q

What is the drug of choice to treat mucosal-stage larvae (including hypobiosed larvae).

A

Moxidectin

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13
Q

Describe the features of disease with Cyathostomin

A
  • Larval cyathostominosis
  • Occurs when large numbers of mucosal-stage larvae (L3, L4) build-up in the mucosa of large intestine
  • Mass emergence of mucosal-stage hypobiosed larvae
  • 50% fatality rate
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14
Q

What are the clinical signs of Cyathostomin infection?

A
  • Sudden onset diarrhoea/ weight loss
  • Sudden weight loss/oedema
  • Acute diarrhoea, weight loss and collapse
  • Colic
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15
Q

What are 3 predisposing factors for Cyathostomin infection?

A
  • Age (≤5yrs)
  • High stocking density
  • History of poor parasite control
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16
Q

Larval cyathostominosis occurs at what time of year?

A

October - may

17
Q

Which host factors affect the epidemiology of Cyathostomin?

A
  • Hypobiosis = Arrested, mucosal cyathostomins are a major source of infection year to year
  • Age and Immune status
  • Animals <3 years of age have highest levels of infection
18
Q

Describe over dispersion in Cyathostomin infections

A

Over dispersion – small proportion of the host population carries the majority of the parasite population
80% egg shedding by 20% horses - small portion of the population will have high FECs

19
Q

Give some environmental factors which influence the epidemiology of Cyathostomin

A
  • Continuous source of eggs being passed onto pasture by infected horses
  • Eggs to L3 development is temperature dependent
  • L3 can survive overwinter on pasture
20
Q

Describe April-June in a typical year of Cyathostomin

A
  • Overwintered L3 on pasture
  • Once ingested L3 mature, PPP = six-eight weeks
  • Eggs start to be passed onto pasture in faeces: continuous excretion of eggs
  • Hypobiotic larvae within the host are mature and become adults. They are a source of eggs passed onto pasture
  • Ambient temperatures gradually start to increase, eggs start to develop more rapidly
21
Q

Describe July-September in a typical year of Cyathostomin

A
  • Egg and L1-L3 development is temperature dependent
  • Highest egg shedding is seen in July/August
  • Peak of L3 on pasture in late summer (August/September)
22
Q

Describe October - December in a typical year of Cyathostomin

A
  • L3 on pasture exposed to drop in temperatures

* Cyathostomins: L3 ingested undergo hypobiosis. Accumulation of hypobiosed EL3/L4 in large intestinal mucosa.

23
Q

Describe January-March in a typical year of Cyathostomin

A

Cyathostomins: Larval development resumes and mucosal stages mature and trickle emerge

Y3 Parasitology S2 (13 decks)

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